walterhimmel1
S40 Control Unit Communication Error
Summary of the thread
A 2006 Volvo S40 was experiencing a control unit communication error, overheating, check engine light, and coolant spills. The suspected cause was a bad cable or plug connection. Suggestions included checking the CAN bus wiring harness, particularly around the ECU, and considering a workshop diagnosis for potential software glitches or control module issues. The problem was resolved by fixing a faulty connection, costing 95€.
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4 comment(s)
walterhimmel1 (community.author)
CAN bus wiring, noted. Thanks! Not running rough, though. Just the overheating and coolant. Where exactly should I be looking for this CAN bus issue? Any specific control module connections that are prone to this?
clara_schaefer16
On my S40 it was around the ECU. If the engine isn't running rough, it might be a software glitch or a more serious control module problem. Honestly, with the overheating and coolant loss on top of the comm error, I'd probably take it to a workshop to get properly diagnosed. Could be more than just a dodgy wire.
walterhimmel1 (community.author)
Thanks, I appreciate the advice. Turns out it was a faulty connection as suspected. Cost me 95€ to fix. Everything is running smoothly now.
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VOLVO
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S40
clara_schaefer16
I had a similar problem with my S40. Overheating and check engine light, plus coolant issues. Did you check the CAN bus wiring harness for any obvious damage? It might be a long shot, but is the car running rough?